The present invention relates to the discovery, identification, and characterization of novel human polynucleotides encoding proteins that share sequence similarity with mammalian membrane proteins. The invention encompasses the described polynucleotides, host cell expression systems, the encoded proteins, fusion proteins, polypeptides and peptides, antibodies to the encoded proteins and peptides, and genetically engineered animals that either lack or over express the disclosed genes, antagonists and agonists of the proteins, and other compounds that modulate the expression or activity of the proteins encoded by the disclosed genes that can be used for diagnosis, drug screening, clinical trial monitoring, the treatment of diseases and disorders, and cosmetic or nutriceutical applications.
Membrane proteins can serve as recognition markers, mediate signal transduction, and can mediate or facilitate the passage of materials across the lipid bilayer. As such, membrane proteins, are proven drug targets.
The present invention relates to the discovery, identification, and characterization of nucleotides that encode novel human proteins and the corresponding amino acid sequences of these proteins. The novel human proteins (NHPs) described for the first time herein share structural similarity with mammalian sodium-calcium exchanger proteins, sodium-calcium potassium exchanger proteins, and potassium dependent versions of the same.
The novel human nucleic acid sequences described herein encode alternative proteins/open reading frames (ORFs) of 603, 316 and 353 amino acids in length (SEQ ID NOS: 2, 4, and 6).
The invention also encompasses agonists and antagonists of the described NHPs, including small molecules, large molecules, mutant NHPs, or portions thereof, that compete with native NHP, peptides, and antibodies, as well as nucleotide sequences that can be used to inhibit the expression of the described NHPs (e.g., antisense and ribozyme molecules, and open reading frame or regulatory sequence replacement constructs) or to enhance the expression of the described NHPs (e.g., expression constructs that place the described polynucleotide under the control of a strong promoter system), and transgenic animals that express a NHP sequence, or xe2x80x9cknock-outsxe2x80x9d (which can be conditional) that do not express a functional NHP. Knock-out mice can be produced in several ways, one of which involves the use of mouse embryonic stem cells (xe2x80x9cES cellsxe2x80x9d) lines that contain gene trap mutations in a murine homolog of at least one of the described NHPs. When the unique NHP sequences described in SEQ ID NOS:1-7 are xe2x80x9cknocked-outxe2x80x9d they provide a method of identifying phenotypic expression of the particular gene as well as a method of assigning function to previously unknown genes. In addition, animals in which the unique NHP sequences described in SEQ ID NOS:1-7 are xe2x80x9cknocked-outxe2x80x9d provide a unique source in which to elicit antibodies to homologous and orthologous proteins that would have been previously viewed by the immune system as xe2x80x9cselfxe2x80x9d and therefore would have failed to elicit significant antibody responses. To these ends, gene trapped knockout ES cells have been generated in murine homologs of the described NHPs.
Additionally, the unique NHP sequences described in SEQ ID NOS:1-7 are useful for the identification of protein coding sequence and mapping a unique gene to a particular chromosome. These sequences identify actual, biologically relevant, exon splice junctions as opposed to those that might have been predicted bioinformatically from genomic sequence alone. The sequences of the present invention are also useful as additional DNA markers for restriction fragment length polymorphism (RFLP) analysis, and in forensic biology.
Further, the present invention also relates to processes for identifying compounds that modulate, i.e., act as agonists or antagonists, of NHP expression and/or NHP activity that utilize purified preparations of the described NHPs and/or NHP product, or cells expressing the same. Such compounds can be used as therapeutic agents for the treatment of any of a wide variety of symptoms associated with biological disorders or imbalances.
The Sequence Listing provides the sequences of the NHP ORFs encoding the described NHP amino acid sequences. SEQ ID NO:7 describes a polynucleotide encoding a NHP ORF with regions of flanking sequence.